(a) Technical Field
The present disclosure relates, in general, to a method for cold starting a fuel cell vehicle. More particularly, it relates to a method for more efficiently cold starting a fuel cell vehicle which has been left at a low temperature for a long period of time.
(b) Background Art
In general, a typical fuel cell system which is applicable to a hydrogen fuel cell vehicle as an environmentally-friendly vehicle comprises a fuel cell stack for generating electricity by an electrochemical reaction between reactant gases, a fuel processing system (FPS) for supplying hydrogen as a fuel to the fuel cell stack, an air processing system (APS) for supplying oxygen containing air as an oxidant required for the electrochemical reaction in the fuel cell stack, a thermal management system (TMS) for removing reaction heat from the fuel cell stack to the outside of the fuel cell system, controlling operation temperature of the fuel cell stack, and performing water management function, and a system controller for controlling the overall operation of the fuel cell system.
Preferably, the fuel processing system comprises a hydrogen tank, high-pressure and low-pressure regulators, a hydrogen valve, and a hydrogen recirculation system, the air processing system comprises an air blower, an air valve, and a humidifier, and the thermal management system comprises a coolant pump and a radiator.
High-pressure hydrogen supplied from the hydrogen tank of the fuel processing system sequentially passes through the high-pressure and low-pressure regulators and is then supplied to the fuel cell stack at a low pressure. Preferably, a blower is installed in a recirculation line of the hydrogen recirculation system to recirculate unreacted hydrogen exhausted from an anode (“hydrogen electrode”) to the anode, thus recycling the hydrogen.
One consideration of the fuel cell vehicle having the above-described fuel cell system is to ensure cold startability.
In present fuel cell systems, when a load is applied to a fuel cell, which has been exposed to sub-zero temperatures for a long time (cold soaking), during initial start-up, water produced in a cathode (“air electrode”) by the electrochemical reaction freezes by cold air of the fuel cell stack itself and air at a temperature below the freezing point supplied to the cathode, thus blocking various flow fields and a gas diffusion layer of the fuel cell stack and, at the same time, cutting off the air supply to a cathode catalyst layer. As a result, the voltage of the fuel cell stack is not maintained suitably constant, which makes it difficult to ensure the cold startability.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.